Ingredients

1 1/2 pounds ground sirloin, round or chuck
4 tablespoons garlic-herb butter, cut into 4 half-inch slices (see recipe below)
Coarse salt and black pepper
4 slices pancetta (Italian bacon, optional)
4 slices white Cheddar cheese (optional)
4 hamburger buns or kaiser rolls
2 tablespoons melted butter

Directions

Wet your hands with cold water. Divide beef into 4 portions. Pat each portion into a thick patty filled with a slice of herb butter. Season with salt and pepper and refrigerate the burgers, covered, on a plate lined with plastic wrap while you preheat the grill to high. Grill the pancetta, if using, until golden brown. Transfer to a plate lined with paper towels to drain. Place burgers on the hot grate and season again with salt and pepper. Grill until cooked through, 5-7 minutes per side. If using cheese or pancetta, place a slice on each of the burgers after you've turned it. To test for doneness, insert an instant-read thermometer through the side of the burger into the center. It should read at least 160 degrees for medium. Brush the buns with melted butter and toast on the grill. Assemble with lettuce leaves, onion, tomato and condiments.